clamp micro-optimization

src/textual/geometry.py

@@ -33,8 +33,13 @@ T = TypeVar("T", int, float)
 
 
 def clamp(value: T, minimum: T, maximum: T) -> T:
-    """Adjust a value so it is not less than a minimum and not greater
-    than a maximum value.
+    """Restrict a value to a given range.
+
+    If `value` is less than the minimum, return the minimum.
+    If `value` is greater than the maximum, return the maximum.
+    Otherwise, return `value`.
+
+    The `minimum` and `maximum` arguments values may be given in reverse order.
 
     Args:
         value: A value.
@@ -45,12 +50,18 @@ def clamp(value: T, minimum: T, maximum: T) -> T:
         New value that is not less than the minimum or greater than the maximum.
     """
     if minimum > maximum:
-        maximum, minimum = minimum, maximum
-    if value < minimum:
-        return minimum
-    elif value > maximum:
-        return maximum
+        # It is common for the min and max to be in non-intuitive order.
+        # Rather than force the caller to get it right, it is simpler to handle it here.
+        if value < maximum:
+            return maximum
+        if value > minimum:
+            return minimum
+        return value
     else:
+        if value < minimum:
+            return minimum
+        if value > maximum:
+            return maximum
         return value
 
 

tests/test_geometry.py

@@ -62,6 +62,14 @@ def test_clamp():
     assert clamp(10, 0, 10) == 10
     assert clamp(5, 10, 0) == 5
 
+    # range in reverse order
+    assert clamp(5, 10, 0) == 5
+    assert clamp(-1, 10, 0) == 0
+    assert clamp(11, 10, 0) == 10
+    assert clamp(0, 10, 0) == 0
+    assert clamp(10, 10, 0) == 10
+    assert clamp(5, 0, 10) == 5
+
 
 def test_offset_bool():
     assert Offset(1, 0)